diff --git a/doc/posix1003.1/ch06.t b/doc/posix1003.1/ch06.t
index 0178ad81e4..d9169a0f12 100644
--- a/doc/posix1003.1/ch06.t
+++ b/doc/posix1003.1/ch06.t
@@ -16,6 +16,8 @@
 pipe(), Function, Dummy Implementation
 @end example
 
+NOTE: pipe() returns ENOSYS.
+
 @section File Descriptor Manipulation
 
 @subsection Duplicate an Open File Descriptor